Oral cavity, pharynx, larynx

Question 1

What are the borders of the oral cavity?

Answer 1

• Superior: palate(hard palate, soft palate), teeth
• Posterior: oropharynx
• Inferior: floor of mouth, tongue and teeth
• Lateral: cheeks

Question 2

Describe the anatomy of the hard palate

Answer 2

The palate forms the superior border of the oral cavity
Hard palate = the anterior part of the palate. Has a bony structure. consists of
* Palatine process of maxilla
* Horizontal plates of palatine bones

Question 3

Describe the anatomy and function of the soft palate (location, attachments, anatomy, muscles comprising)

Answer 3

• A moveable fold attached to the posterior edge of the hard palate that separates the nasopharynx superiorly and the oropharynx inferiorly
• Prevents regurgitation into the nasal cavity
• Extends posterio-inferiorly into a curved free margin (the uvula).
• Comprises 5 muscles:
  1. Levator veli palatini
  2. Tensor veli palatini
  3. Palatoglossus
  4. Palatopharyngeus
  5. Musculus uvula

Question 4

How many permanent teeth are there? What system should be used to labal dental abnormalities?

Answer 4

There are 32 permanent teeth.
Palmer notation chart

Question 5

Which teeth are most vulnerable during airway manouvres?
What is the minimum normal interdental distance at maximal mouth opening in young adults?

Answer 5

The upper incisors are most vulnerable during airway manoeuvres.
37mm (95% confidence interval)

Question 6

What is the mucous membrane covering the tongue comprised of?

Answer 6

The mucous membrane covering the tongue comprises papillae and posteriorly, lymphoid tissue, known as the lingual tonsils.

Question 7

Describe the structure and function of the tongue

Answer 7

A muscular organ in the floor of the mouth. Together with the teeth and the floor of the mouth, forms the inferior border of the oral cavity.
Function:
* Squeeze food into the pharynx
* Assist in word formation
Structure:
* Covered by a mucous membrane comprising papillae and lymphoid tissue
* Extrinsic muscles (originate outside the tongue and insert into it. Responsible for tongue movement.)
* Intrinsic muscles (responsible for alterations of tongue shape)

Question 8

Describe the extrinsic muscles of the tongue

Answer 8

The extrinsic muscles originate outside the tongue and insert into it. They are responsible for tongue movement.
1. Genioglossus
2. Hyoglossus
3. Styloglossus
4. Palatoglossus

Question 9

Describe the intrinsic muscles of the tongue

Answer 9

The intrinsic muscles of the tongue are responsible for alterations of shape
* Inferior longitudinal muscle
* Superior longitudinal muscle
* Transverse muscle
* Vertical muscle

Question 10

Describe the innervation of the tongue

Answer 10

Motor function:
* hypoglossal nerve (CN XII)
* except palatoglossus, which is supplied by a branch of the vagus nerve (CN X)

Sensation:
* Anterior 2/3: general sensation supplied by lingual nerve, a branch of CN V3 (mandibular branch of trigeminal). Taste supplied by chorda tympani from facial nerve (CN VII)
* Posterior 1/3: lingual branch of glossopharyngeal (CN IX) supplies general sensation and taste

Parasympathetic secretory function: chorda tympani from facial nerve (CN VII)

Question 11

Describe the anatomy and function of the floor of the mouth
Which muscles make up the floor of the mouth

Answer 11

Forms part of the inferior border of the oral cavity. Provides a muscular bed on which the tongue rests, and a framework for two glands:
* sublingual
* submandibulary salivary

Muscular bed consists of:
* Digastric and stylohyoid: arising at skull base and inserting into the floor of the mouth
* Mylohyoid: spans the mandible, forms a sling across the floor of the mouth

Question 12

Name 3 factors that contribute to mouth opening
What is the minimum normal interdental distance at maximal mouth opening in young adults?

Answer 12

Temperomandibular joint
Mandibular length
Cranio-cervical mobility

37mm (95% confidence interval)

Question 13

Describe the pharynx

Answer 13

The pharynx is a funnel-shaped fibromuscular tube that is the common passage for air into the trachea and food into the oesophagus

The interior of the pharynx can be divided into
* Nasopharynx
* Oropharynx
* Laryngopharynx

Question 14

Describe the muscular structure of the pharynx

Answer 14

The pharyngeal skeleton is made up of a fibromuscular tube with external circular muscles and inner longitudinal muscles.

External circular muscles (made up of the constrictor muscles)
* Responsible for propelling food into the oesophagus
* Superior constrictors
* Middle constrictors
* Inferior constrictors

Inner longitudinal muscles
* Responsible for elevating the larynx and pharynx during swallowing and speaking
* Stylopharyngeus
* Palatopharyngeus
* Salpingopharyngeus

Question 15

Name the external circular muscles of the pharynx

Answer 15

• Superior constrictor
• Middle constrictor
• Inferior constrictor

Question 16

Describe the innervation of the pharynx

Answer 16

Nerve supply to the pharynx is mainly via the pharyngeal plexus, which contains branches from the
* glossopharyngeal (CN IX)
* vagus (CN X)
* accessory (CN XI)

Motor innervation:
* Pharyngeal branches of the accessory nerve, which run alongside the vagus

Sensory innervation:
* Mostly pharyngeal branches of CN IX
* Except the nasopharynx, which is supplied mainly by the maxillary branch of the trigeminal (CN V2)

Question 17

How does the gag reflex work? Describe the function and innervation

Answer 17

• This reflex prevents noxious material going into the pharynx or trachea. It is not stimulated during eating.
• Following stimulation of the soft palate or posterior tongue, there is reflex contraction of the soft palate.
• Sensory innervation: CN IX (glossopharyngeal)
• Motor reflex of the soft palate: vagal innervation.

Question 18

Name the inner muscles of the pharynx

Answer 18

Stylopharyngeus
Palatopharyngeus
Salpingopharyngeus

Question 19

Describe the nasopharynx

Answer 19

• lies posterior to the nasal choana and superior to the soft palate.
• the sphenoid bone lies posteriorly and superiorly with overlying lymphoid tissue known commonly as the adenoids.
• the auditory tubes arise on the lateral wall

Question 20

What are the borders of the oropharynx

Answer 20

The oropharynx is the posterior extension of the oral cavity.
* Superior border = soft palate
* inferior border = base of tongue
* Lateral walls = palatopharyngeal arches. The palatine tonsils (commonly called the tonsils) lie within the arches

Question 21

Describe the laryngopharynx

Answer 21

The laryngopharynx is the area posterior to the larynx

• Extends from the superior border of epiglottis to the cricoid cartillage
• Posterior and lateral walls are made up of constrictor muscles
• Communicates with the larynx via the laryngeal inlet. The piriform recesses are found on either side of the laryngeal inlet

Question 22

Which area of the pharynx is particularly vulnerable to damage during instrumentation

Answer 22

The pharynx is lined with fragile mucous membranes, which can be damaged during instrumentation.
Perforation of the pharyngeal or oesophageal mucosa –> mediastinitis (high mortality)
The laryngopharynx is particularly vulnerable due to its lack of underlying serosal layer and relatively few supporting structures.

Question 23

Describe the structure (general) and functions of the larynx

Answer 23

The larynx is a valve that
* protects the tracheobronchial tree from aspiration of food and liquid
* is responsible for phonation

• The skeletal structure is made up of 9 cartillages.
• The thyrohyoid ligament and membrane connects the thyroid cartillage to the hyoid bone and suspends the larynx
• The extrinsic muscles (infrahyoid and suprahyoid) move the larynx as a whole
• The intrinsic muscles alter the length and tension of the vocal cords
• The interior of the larynx can be divided into three sections (vesibule, ventricle, infraglottic cavity) by the vestibular folds

Question 24

Describe the skeletal structure (cartillages, ligaments) of the larynx

Answer 24

The skeletal structure is made up of nine cartillages:
* Thyroid
* Cricoid
* Arytenoids (x2) - paired, and found at the posterior aspect of the laryngeal inlet
* Corniculate (x2)
* Cuneiform (x2)
* Epiglottic

The thyrohyoid ligament and membrane connects the thyroid cartilage to the hyoid bone and suspends the larynx
The cricothyroid membrane connects the lower edge of the thyroid cartilage with the cricoid cardilage

Question 25

Which membrane is punctured for emergency oxygenation and why?

Answer 25

Cricothyroid membrane (cricothyroidotomy) * Usually easily palpable * The cricoid cartillage is a complete ring * A size 6mm endotracheal tube may be inserted through it.

Question 26

Describe the muscles (names, function) of the larynx

Answer 26

Extrinsic muscles: move the larynx as a whole. Divided into 2 categories: * Infrahyoid muscles: depress the hyoid bone and larynx * Suprahyoid muscles: elevate the hyoid and larynx The intrinsic muscles alter the length and tension of the vocal folds * Cricothyroid * Cricoaretenoideus * Aretenoideus (not shown in diagram) * Aryepiglotticus * Thyroarytenoideus * Thyroepiglotticus

Question 27

Describe the interior of the larynx

Answer 27

The vestibular folds contain the vestibular ligament and are covered by mucous membrane. These folds divide the interior of the larynx into three sections: * Vesibule: superior to the folds, includes the epiglottis, piriform fossae, valleculae * Ventricle: superior to vocal folds but inferior to vestibular folds * Infraglottic cavity: the area between the vocal folds and the cricoid cartillage

Question 28

Describe the innervation of the larynx

Answer 28

Vagus nerve, via the superior and recurrent laryngeal nerves Superior laryngeal nerve: divides into * internal laryngeal nerve: sensory supply to the mucous membrane above the vocal folds * external laryngeal nerve: motor supply to the inferior constrictor and cricothyroid Recurrent laryngeal nerve * runs beween the oesophagus and the trachea, and over the medial aspect of the thyroid * motor supply to all intrinsic muscles except cricothyroid * sensation to all surfaces below the level of the vocal cords

Question 29

What would be the effects of a lesion to the recurrent laryngeal nerve or superior laryngeal nerve

Answer 29

The SLN and RLN provide innervation of the larynx. The RLN is particularly vulnerable to injury during thyroidectomy, carotid endarterectomy, and operations of the anterior triangle of the neck. RLN palsy -> * paralysis of all muscles of larynx except cricothyroid and loss of sensation between the vocal folds * unilateral: hoarseness, weak cough * bilateral: can cuase airway obstruction and/or hoarseness SLN palsy -> * Loss of sensation above vocal folds and/or paralysis of cricothyroid * Hoarseness

Question 30

Which part of the larynx matches each function? 1. Suspends the larynx 2. Depresses the hyoid bone and larynx 3. Connects the lower edge of the thyroid cartilage with the cricoid cartilage 4. Elevates the hyoid and larynx 5. Alters the length and tension of the vocal folds

Answer 30

1. Thyrohyoid ligament and membrane 2. Infrahyoid muscles 3. Cricothyroid membrane 4. Suprahyoid muscles 5. Intrinsic muscles of larynx

Question 31

Answer 31

Question 32

What problems would each lesion cause?

Answer 32